IJE TRANSACTIONS A: Basics Please cite this article as: S. M Seyed Hosseini *, K Shahanaghi, S Shasfand, Functional model of integrated maintenance in petrochemical industries, International Journal of Engineering (IJE), IJE 184-191 International Journal of Engineering Journal Homepage: www.ije.ir Functional model of integrated maintenance in petrochemical industries Seyed Mohammad Seyed Hosseini 1 *, Kamran Shahanaghi 2 , Safar Shasfand 3 1 Professor, Department of Industrial Engineering, Iran University of Science and Technology, Tehran, Iran 2 PhD, Department of Industrial Engineering, Iran University of Science and Technology, Tehran-Iran 3 PhD student, Iran University of Science and Technology, Tehran, Iran, and Maintenance manager of Tabriz Petrochemical Company, Tabriz, Iran. PAPER INFO Paper history: Keywords: Maintenance Management Manpower Equipment Knowledge Cost Energy ABSTRACT The purpose of this research is to provide an integrated maintenance model in the petrochemical industry. The current research is applied in terms of purpose and descriptive survey in terms of data collection method. A mixed method (qualitative and quantitative) has been used to conduct the research. The tools used in this research are researcher-made questionnaires (36 Questions), dialog with domestic and foreign professors in the field of maintenance and production, the Delphi technique (41 Maintenance managers), Field investigations(20 internal and 7 overseas petrochemical companies), and experiences and evidence obtained from 12 overhauls during 30 years. The validity was determined through experts' opinions and reliability through Cronbach's alpha evaluation. The results showed that the questionnaire has high validity and reliability. The statistical population includes experts in the field of Maintenance in industry and university, among whom 110 people were selected by targeted sampling. To conduct the research in the first stage, first by using the documentary method and content analysis and interviews with experts, the indicators and dimensions of the strong integrated maintenance and repair model were extracted and given to the experts in the form of a Likert scale for scoring; After conducting the survey, 36 components were selected, and each component of management, manpower, equipment, and knowledge had 9 sub-components. In the next step, the components and sub- components were scored and ranked using the questionnaire and the Analytical hierarchy process method. In this research, the following three results have been obtained: 1- Four main roots(Human, Management, Knowledge, and Equipment) and thirty-six sub-roots of effective maintenance. 2- The essential elements of the formula for measuring the criticality index of equipment.3- Five indicators for measuring integrated maintenance performance. According to the calculations, the inconsistency between the vectors of each matrix is less than 0.10. Therefore, the constituent vectors of each of the formed matrices are consistent with the three results of the research and the stability of the respective comparisons is acceptable. 1. INTRODUCTION 1 Maintenance is one of the basic concepts in advanced organizations and moving towards world-class and has a special place among industry managers. Today, Maintenanceare of particular importance with the demand for productivity, quality, and availability of equipment [1], Maintenance systems directly affect the budget and *Corresponding Author Email: seyedhosseini@iust.ac.ir) profitability of industries, and the lack of proper planning of Maintenance in the organization reduces the useful life of the equipment [2], extensive attention to the science of Maintenance is necessary to respond to the expectations of industries, which due to the limited resources such as energy, manpower, and capital, with correct planning and its principled implementation, can lead to an increase in